A storm buried Skara Brae for centuries, and it would take a storm to unearth it again.

Roughly 5,000 years ago, a small community of farmers settled in the village on a small island off Scotland's northeast coast. The villagers lived in geometrically identical stone houses, grew barley, raised cattle and sheep, and carved tools using volcanic rock from Iceland that washed ashore. Over 700 years, they built an ordered society until, archaeologists believe, the climate changed and powerful storms buried the village in water and sand.

Almost three centuries later, in 1850, another powerful storm tore into the island's coastal dunes, revealing Skara Brae once more. Archaeologists have been excavating the site ever since, gaining detailed insights into the uniquely organized and comfortable Neolithic settlement. But now the climate is changing again, and it may not be long before Skara Brae is reclaimed by the ocean.

As countries around the world, including the United States, are pondering how they might protect their historic sites from the threats of climate change, Scotland is showing them the struggles they may have to look forward to.

Climate change is chewing into Scotland's 6,000-mile coastline at an alarming rate. Precipitation is doubling in some areas of Scotland. Sea levels are rising, and the coastline is eroding. An increasingly hostile Atlantic Ocean is battering the soft, sandy shores with violent storms, and the trend is both unearthing hosts of undiscovered ancient sites and putting them in immediate danger of being lost again.

Skara Brae is one of 8,000 "scheduled" historic sites the Scottish government has prioritized as nationally important, and the government is now investing millions of dollars into protecting those sites from powerful storms and coastal erosion.

Rod McCullagh, deputy head of archaeology strategy at Historic Scotland, said the country's oldest historic sites have already been lost to sea-level rise.

More and more sites, and less time to save them
"You can argue in face of that that we're a long way behind where we should be, but because we are facing it now rather than possibly 20 years' time, we're being forced to do something," he added.

This includes using hard engineering to fortify some sites, including building sea walls, installing rock armoring, and soft engineering, like seeding sand dunes with marrim grass to stabilize them. One of the most successful restorations has been at the Links of Noltland, a prehistoric settlement where vegetation has been planted to stabilize collapsing dunes.

Most of Historic Scotland's scheduled monuments are privately owned, and the owners of the sites aren't obligated to do anything to protect them, according to Mairi Davies, climate change manager for the agency. There are about 260,000 historic sites in the country in total, and the schedule acts as a shortlist of sorts, identifying the roughly 3 percent that are of the highest national significance.

The schedule is dynamic and often changes, for both cultural and physical reasons.

Storms and eroding coastlines can help destroy sites, removing them from the schedule, and help discover sites, adding them to the schedule.

"If a site is compromised by coastal erosion, that might be reason to remove it from the schedule, because it's no longer of national importance," Davies said.

"There are over 8,000 scheduled monuments, many of which are on the coast," she added. "Obviously, not all of those are going to survive the kind of coastal erosion that we're experiencing here."

Furthermore, improvements in archaeological science and analysis mean that sites that may have been dismissed in the past as not historically and culturally valuable may now give detailed insights into ancient Scotland.

McCullagh said child burial sites—which in the past would have been respected, but not considered an information-rich resource—are now actually worth saving. Archaeologists can discern the year-by-year diet of a child just by analyzing the milk teeth left behind in the grave.

"Things which we thought weren't worth saving are actually worth saving now," he said. "That's part of the alarm."

And amid the immediate threats of climate change, with more and more historic sites being discovered, and with archaeologists able to extract more information from them, the question of what is "nationally significant" may still be the hardest question to answer.

"If you want two archaeologists to argue to blows, ask them what's nationally significant," McCullagh said.

'Loss will happen'
Scotland is ahead of most of the world in many ways when it comes to protecting historical sites from the aggressions of climate change. Its government has a comprehensive list of historic sites, and has identified the main priorities within those sites. It is already taking steps to protect some sites, and for some others, it is pursuing a "managed retreat," allowing seawater to reclaim some ancient structures and tidal flats—stretches of sand that can be so pristine they still contain cattle footprints from thousands of years ago.

"What we have been looking for is saying that, effectively, loss will happen, so how do we acquire benefit from physical loss? And how can we preserve something of the physical remains by acquiring information about them?" McCullagh said.

But managing the preservation—or sacrifice—of these monuments is difficult, especially for governments that have to stick to budgets. It's hard to determine exactly how much Historic Scotland spends to protect historic sites from the threats of climate change. The agency's 2012-13 annual report lists investments of almost £12 million through Historic Building Repair Grants and a further £213,678 through Ancient Monument Grants.

"You can predict the extent of the impact, but you can't predict when," McCullough said. "If you can't plan—and therefore can't manage a budget to meet it—it's very difficult to respond."

Still, experts in the United States are impressed with what Scotland has achieved so far—especially when compared with American efforts at protecting U.S. historical sites from the threats of climate change. The Union of Concerned Scientists released a report earlier this year identifying almost two dozen sites of historical, cultural and operational importance in the United States in immediate danger from varying climate threats (ClimateWire, May 21).

Jeffrey Altschul, president of the Society for American Archaeology, said the United States could soon find itself dealing with issues similar to Scotland's. Alaska, for example, shares many of the same threats as Scotland: a rich archaeological history on a lengthy coastline, and immediate threats from rising seas, erosion and violent storms.

"[Scotland has] made a conscious decision to let some things go, and that's something we're not good at," Altschul said. "The fact is, there will be a discovery situation [in America soon]."

Not everyone agrees that historical sites should be prioritized. John Hurd, of the International Council on Monuments and Site, said nations should strive to protect every historical site if possible—primarily by leaving it up to local governments and municipalities to manage their preservation. If prioritization must occur, he added, it should be based on vulnerability, not cultural value.

But as the Scottish are learning, most defenses against the impacts of climate change are inherently impermanent.

"All you do with a coast that's changing shape is reinforce and rebuild, and reinforce and rebuild," McCullough said. "In the long term, it's hard to see that as being sustainable."